Development conditions: The solvent is allowed to migrate until the front reaches a line 15 cm from the starting line.

Detection: The plate is examined under ultraviolet light at a wavelength of maximum output of about 254 nm, and then left in a chromatographic chamber containing some iodine crystals until spots appear.

Results: The reference solution of benzathine benzylpenicillin shows numerous spots of different intensities. No additional spots are observed from the solutions of each of the samples subjected to procedures A and B, and the intensities remain the same.

Ultraviolet spectrophotometry

A reference solution in methanol shows three absorption maxima at 251 nm, 257 nm and 263 nm. A maximum appears with time at a wavelength of 312 nm.

The characteristics of the absorption spectra of the solutions of the substances subjected to procedures A and B are modified. An additional maximum at 293 nm appears that increases between procedures A and B.

Infrared spectrophotometry

No change is observed after procedures A and B.

Differential scanning calorimetry

No significant change is observed after procedures A and B.

Conclusion

Benzathine benzylpenicillin is subject to decomposition under accelerated degradation conditions as determined by ultraviolet.